The present invention is a method of making a flexible brain probe assembly.
Creating a probe that contacts the brain tissue represents a challenge to researchers. Researchers typically wish to measure electrical activity at specific sites within the brain that share a well-defined physical relationship to one another. Probes produced by photolithographic techniques, such as the probe designed by personnel at the University of Michigan that is known in the industry and research community as the xe2x80x9cUniversity of Michigan Probe,xe2x80x9d permit the accurate placement of electrode sites that are sufficiently small to permit the measurement of electrical activity at a specific set of predefined sites within the brain. Unfortunately, the desire to use photolithography has prompted the use of silicon as a substrate. Because this material is quite brittle, the use of it creates a risk of breakage inside the brain, endangering the subject or patient and limiting the insertion strategies available to researchers. Moreover, the use of silicon prevents the University of Michigan probe from moving with the brain, which does move about slightly within the skull. In addition, silicon is subject to some restoring force, which tends to cause a silicon probe to migrate over time. Both of these drawbacks have the potential result of causing trauma to the brain tissue.
Another type of probe that is currently available includes a set of insulated wires having laser created apertures exposing electrode sites. Although this type of probe is useful for many applications, it does not yield the precision or the freedom of electrode placement that the University of Michigan probe permits.
A nerve cuff is a device for wrapping about a nerve to electrically stimulate and/or receive electric signals from the nerve. The production of nerve cuffs has also been problematic as the fine scale of the needed features has been difficult to produce on a flexible substrate capable of being wrapped about a nerve.
What is needed but not yet available is an electrode probe and method of making the same that affords unconstrained and accurate placement of the electrodes, but offers flexibility and robustness and is thereby less susceptible to breakage than currently available probes.
In a first separate aspect, the present invention is a method of producing an electrode bio-probe assembly, using a flexible substrate comprising a polymeric layer bearing a conductive material coating. Photolithography and electroplating are used to form a set of contacts and conductors on the polymeric layer of the flexible substrate. Also, the flexible substrate is shaped to have a distal end and to be greater than 5 mm long, less than 5 mm wide and less than 1 mm thick.
In a second separate aspect, the present invention is a method of producing a nerve cuff assembly for application to a target nerve. The method includes the use of photolithography and electroplating to form a set of contacts and conductors on the polymeric layer of a flexible substrate having a polymeric layer and bearing a conductive material coating. The flexible substrate is sized and shaped to fit about the target nerve.